Although a first solution for this problem is already available in the App Store, there are still some shortcomings (no landscape, no iWork docs) apparent in this app. I'm fully convinced we'll see this app in much better shape soon, but until then do this: Simply send the docs via email to yourself.

That's it - you can view a lot of document types in Mail -- even in landscape mode.

I've been using Filemagnet also and find it works very well. They have promised more file types, landscape mode, and so forth. Good price, also. Works only from a Mac, so Windows and Linux users are out of luck. Costs $5.

I also use FileMagnet, and it works very well! I'm looking forward to the developer improving it (but not over-complicating it) over time. One obvious shortfall is the lack of landscape mode, as previously mentioned.